PerfectPixel by WellDoneCode

Extension for web developers and markup designers
PerfectPixel allows developers to put a semi-transparent image overlay over the top of the developed HTML and perform pixel perfect comparison between them
--> Extension is AD supported. Ads are injected into extension panel only, no any injections into websites. If you wish to disable ads you can do it in extension Options menu <--
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Please send bug reports and ideas for future versions to:
support@welldonecode.com
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Features:
* Multiple overlays support
* Inversion and scaling support
* Separate overlays for each website
* Overlays are saved between browsing sessions
* Minimalistic easy-to-use UI
* No image size restrictions
* Drag-n-drop file upload support
* Paste from clipboard support
* Keyboard arrow keys and mousewheel support
* Extension works with file:// scheme (local files)
Tips:
* Double-click on header to expand/collapse main window
* Use Shift + arrow keys for 10px position change
Changelog: http://www.welldonecode.com/perfectpixel/changesets/
Shortcuts: http://www.welldonecode.com/perfectpixel/shortcuts/